Connecting plug



g- 1950 B. G. K. KJELL-BERGER ETAL 2, 77

CONNECTING PLUG Filed March 14, 1949 3nventors 50 6097/1; K. K7 2 4-5EPGEQ KARL E. LO/VIVQV/ST u Patented Aug. 8, 1950 OFFICE 2,517,677 CONNECTING PLUG Bo Gustaf Kjell Kjell-Berger and Karl Erik Liinnqvist, Norrkoping, Sweden Application March 14, 1949, Serial No. 81,238

In Sweden March 15, 1948 p The present invention relates to an improved connecting plug for electrical purposes, especially to so-called banana plugs, and connecting sleeves.

The connecting plug according to the invention consists of a metal contact pin provided with a jacket or sleeve of insulating material, which is slipped on to the pin, the contact pin being made in one piece and comprising two channelled branches or arms interconnected by a Web at one end thereof, said web being provided with an inlet for a conducting wire, as well as with stop flanges against which one end of the insulating jacket rests when properly attached.

Additional features of the invention will appear from the following description of the embodiment thereof which is illustrated in the annexed drawing, in which Fig. 1 shows the punched-out contact pin proper before its two branches have been bent towards each other,

Fig. 2 shows the connecting plug after the branches have been bent together and the insulating jacket has been slipped on to them, and

Fig. 3 shows in cross sectional elevation the connecting plug provided with the electric wire.

Fig. 4 shows a longitudinal cross section on line 4-4 of Fig. 3 and Fig. 5 shows in perspective insulating jacket or sleeve member.

As will appear from Fig. l, the contact pin is initially made in one flat piece, preferably by punching it out from sheet metal. The two arms I of said piece are interconnected by a web I! provided with stop flanges 4. Prior to being provided with an insulating sleeve 6, the branches I of the contact pin are channelled as shown in Fig. 1 and bent towards each other along the folding lines 2. As will appear from the figure, they are provided with stops 3.

Fig. 2 shows the connecting plug after the in sulating sleeve 5 has been slipped on to the contact pin, that is, after the branches l have been bent towards each other and the insulating sleeve 5 has been slipped on over the free ends I of thebranches. The stop flanges 4 on the web Ii, against which the sleeve 6 is pressed, support the sleeve at its upper end and retain it in this position through co-operation between the stop flanges 4 and the tendency for the two arms of the contact pin to separate. Stops 3 cooperate to prevent the sleeve 6 from sliding towards the free end i of the pin when the sleeve t has once been mounted thereon. The resiliency of the channelled arms I is increased by cut-outs forum 3 Claims. Cl. 173-363) ing shoulder portions I2 arranged to lie within the insulating sleeve 6, creating a certain interspace I3 between the two arms I and allowing the two arms to be compressed towards each other when the contact pin is inserted in the correspondingelectrical sleeve contact, to insure good electrical contact and a secure seatingfor the plug. For facilitating the insertion of the connecting plug, the free ends I of the arms I may be bent inwardly.

As appears from Fig. 3, the wire it is led through the wire inlet 5 in the web H for connection with the connecting plug and is knotted at 9 to prevent it from being drawn out through the inlet 5 when pulled. Electric contact is effected between the wire and the contact pin by bending the de-insulated end II) of the .wire upwardly about the inner edge of the slit forming the space between the shoulders E2 of the contact pin. When the sleeve 6 is slipped on and fixed on the upper end of the contact pin, the de-insulated, bent end IU of the wire 8 is squeezed against the shoulder portions of the contact pin by the jacket 6, and good electric contact and mechanical retention is thus obtained without soldering. The wire is also secured to the contact pin so that it cannot be pushed downwards within it.

The stops 3 may be disposed further along the arms I of the contact pin so that, when the jacket has been fixed in its position, they are situated inside the sleeve instead of outside of it. In this case a groove for each stop 3 is provided within the sleeve, extending longitudinally thereof, through which the stops 3 can glide when the sleeve is slipped on to the contact pin. When the sleeve is properly mounted and rests against the stop flanges 4, it is then turned, say one-quarter of a revolution, causing the stops to be pressed against the inner wall of the jacket or, preferably, into bayonet slot grooves provided in. the inner wall of the jacket at right angle to the first-mentioned groove. dent, that in this case the contact surface, preventin the jacket from being pushed towards the free end of the pin, will be located within the jacket instead of being constituted by the lower edge of the jacket as in the case first described.

The contacting plug according to the invention possesses many advantages over similar prior art devices. Thus, it is very easy to produce, because it is punched out in one single piece by a simple operation and then, as mentioned before, is simply bent along the lines 2. Apartfrom the con- It is evi tact pin, the connecting plug of this invention comprises one single additional member, viz. the insulating jacket or sleeve 6. This sleeve, which in known devices of a similar kind is screwed to the contact pin, is, according to this invention, simply slipped on to the contact pin and is secured in place by stop flanges 4 and stops 3 in co-operation with the resilient stresses pressing the arms I apart. The wire to be connected with the connecting plug may be of very small dimensions and its junction with the contact pin is not exposed to great stresses. The mechanical load On the wire is absorbed by the knot 9. This stop knot 9 is disposed within the upper portion of the pin so as to be invisible from the outside and rests against the web I I. Since no screws and no solderin are used and the jacket is not screwed on, the assembling of the wire and the connecting plug is very convenient to perform and is very rapidly done. The plug according to the invention, may furthermore have very small dimensions. In spite of the fact that the wire is not soldered to the contact pin, the electrical contact is a good one, as the pressure of the sleeve against the base wire end and the upper portion of the resilient contact pin provides a contact pressure of a sufficient strength.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An electrical connecting plug comprising a one-piece bifurcated contact portion formed of substantially parallel channelled arms and an integral web portion interconnecting one end of each of said arms, an inlet in said web portion for a conducting wire, stop flanges on said web portion, and an insulating sleeve member embracing said arms in, the regionv of said web end portion, one end of said sleeve member resting against said flanges.

2. An electrical connecting plug as claimed in claim 1, comprising raised stops on said arms for retaining the other end of said sleeve member.

3. An electrical connecting plug as claimed in claim 2, comprising contacting channelled shoulder portions on said arms within the region embraced by said sleeve member, forming spaced contact arm portions externally of said shoulder portions.

BO GUSTAF KJELL KJELL-BERGER.

KARL ERIK LoNNQvIsT.

No references cited. 

